Coated metal container



Patented Aug. 1, 1950 2,511,220 con-an METAL CONTAINER Jacque c. Morrell, Marlon, Pa.

No Drawing. Application November as, 1941, Serial No. 788.694

. 6 Claims. (Cl. 220-64) This application is in substance a continuation in part of my application Serial No. 239.283, filed November 7, 1938, and now abandoned, and my application filed April 30, 1941, Serial No. 391,067, now issued as Patent Number 2,412,528.

This invention relates to improvements in receptacles or containers and processes of making the same and refers particularly to receptacles, containers or cans for packaging solid or liquids of mixtures of the same such as foodstuffs and perishables generally.

This invention has for its general object the use of cheaper and/or better materials than those now commonly employed. The materials now used for making ordinary metallic cans or containers are thin sheet iron or steel plated with tin. This has been common practice since the industry began about a century ago and very few improvements have been made in the art in respect of materials employed for the manufacture of cans. For most purposes tin plating is satisfactory to prevent corrosion of the container. However, there are many uses where it is unsatisfactory even though there are some modiflcations in the materials employed where special corrosion conditions are encountered.

In its broadest aspects the present invention consists oi coating a container with a protective layer comprising a primer or undercoatlng and a top coating.

The coatings may be applied to the metal prior to forming into a container or can or after the latter are formed. In general the primer coating is flexible to permit working of the metal such as crimping or curling to attach the tops and bottoms.

It is not the purpose of the present invention to change the method of manufacture of the container or receptacle now employed except insofar as it is necessary to do so in more or less minor detail to adapt the present invention to the present methods of manufacture. It is contemplated applying my invention to all of the methods of manufacture of the receptacle or container per se now employed or which may hereafter be developed, the main purpose or object of the invention being an application of protective coatings or lining to insure against corrosion and to prevent contamination of the contents of the can.

The tops and bottoms of the container may be attached in the usual manner. The ends of the walls may be crimped or curled to permit attachment of the top and bottom in the conventional manner as employed in the metal can or container industry, using a rubber composition or other suitable material to seal the same. The invention is also applicable tospecial forms, such as the self-opening type of cans, which have a relatively narrow strip integral with the metal collar or cylindrical portion or sides of the container at a point beneath the top or lid.

In the modification of my invention, I may employ as a minor or as the principal ingredient of the primer coating, materials which have rubberlike properties, for example: synthetic rubbers, such as butadiene or methyl butadiene polymers or copolymers of butadiene with various substances such as acrylonitrile, styrene, butylenes and the like, polymerized chloroprene, (e. g. neoprene, Duprene, etc.) and similar polymers or copolymers. Other types of synthetic rubbers or rubber-like materials may also be employed such as various chlorinated rubbers and hydrochlorides of rubber, such as Pliofllm, organic polysulphide such as Thiokol, Koroseal, and other types of plasticized vinyl chloride polymers and the like. Solutions of these various materials in suitable solvents usually of an aromatic type may be employed.

As one of the features of the invention, particularly to improve the appearance of the can or container and to give it certain protective properties both inside and outside, the primary flexible layer may be admixed with certain pigments of any desired color, preferably white.

In general, the preferred resin or plastics to be employed are the thermoplastic synthetic resins, e. g., such as the polystyrene, vinyl or Vinyllte types. The vinyl or polystyrene types are most preferred because they have high temperature softening points and are clear and colorless. (The vinyl or Vinylite polymers may include acetates, halides, polyvinyl alcohols plus aldehydes, etc.) Other types of thermoplastic synthetic resins may, however, be employed, among which are the alkyd resins sometimes referred to as Glyptals, which permit oils to dry throughout the film and which are made from polybasic acids such as phthalic and maleic acids and polyhydric alcohol, such as glycerol, glycols, etc., the acrylic or acrylate resins, e. g., methacrylate, vinylidene chloride polymers, etc. These are given by way of example and others might also be mentioned.

A regrouping of the above types of thermoplastic synthetic resins might be shown as (a) styrenes, (11) vinyl resin, (0) alkyds, (d) acrylates. The polystyrenes are colorless, odorless, and tasteless, and are soluble in esters and chlorinated hydrocarbons and are compatible with such plasticizers as dibutyl and homologous phthalates and tricresyl and homologous phosphates. The vinyl resin plastics include, as stated, the polymers of the acetates and esters generally, ethers, halides, polyvinyl alcohols, acetals, and aldehydes, and one of the outstanding thermoplastic resins in this group is made by the copolymerization of vinyl chloride and vinyl acetate, referred to in the trade as Vinylite. The acrylate resins as well as the polystyrenes and vinyls are characterized by the unsaturated radical CH2=CH known as the vinyl radical, and in one sense, therefore, the three types belong to one large family, which may be referred to as the vinyl thermoplastic synthetic resins and may also include divinyl types, and serve to define the entire group.

Resins with accompanying plasticizers such as tricresyl and homologous phthalates and dibutyl and homologous phthalates and the like may also be employed. Although not equivalent to the thermoplastic synthetic resins other plastic materials may in some cases be incorporated therewith in relatively minor amounts, e. g., natural rubbers, synthetic rubbers and other natural and synthetic plastics. Also in order to render the thermoplastic synthetic resin more flexible in some cases plasticizers, drying oils, or softening agents generally in small amounts may be used byv adding the same to the resin; among which may be ethyl, hutyl,amyl esters, phthalates, and tricresyl phosphate and triphenyl phosphate. Small amounts of drying oil may also be added to the resin.

The primer coating is preferably dissolved in a solvent and applied to the surfaces of the container after which the solvent is evaporated leaving a. film of the primers. The thermoplastic synthetic resin surface coating is then applied over this film also in a thin film, preferably in solution in a suitable solvent and the latter is removed and the resin film dried at a temperature of approximately 200 to 400 F. The solvents employed with these, the resin and plasticizer materials, comprise generally the alcohols, ethers, ketones, aldehydes, esters or mixtures, in general relatively low boiling also various hydrocarbons and derivatives.

The top or surface coating is composed mainly of resins. Generally it is not necessary to introduce pigments into the top coating, as this is purely a protective coating and will be transparent enough ordinarily for the pigment of the bottom coating to be seen therethrough. Where the pigment in the bottom or primer coating reduces the flexibility thereof too greatly it may be placed in the top coating, using care and precaution to avoid destroying the hardness, gloss and homogeneity of the top coating. The amount of solvent employed should be suflicient to permit ready application of the top coating by spraying, brushing or dipping and this, of course, applies to the bottom coating also. Usually two to three times the amount of the solvent by weight of the resin employed will suflice, although this is varied in accordance with the requirements as stated.

4 being crimped to attach the tops and bottoms to the body to maintain it in a sufllciently heated condition to permit the thermoplastic resin to soften somewhat while working the same. Also in all of the modilcations described it is intended to cover the metal parts of the container so as to permit working the same in the conventional manner to allow proper closure for the purpose of scaling up the contents.

The term "primer coating as used herein means an undercoating in contradistinction to a top or surface coating.

It will be understood that the various specific substances and percentages of materials shown herein are given by way of illustration, and that the invention is not limited thereto; also that there may be many modifications and departures within the broad spirit and scope of the invention.

1 claim as my invention:

1. A container comprising a, body, a top and a bottom of sheet metal and at least the interior of which is coated with a relatively flexible prime coating comprising a synthetic rubber composed of carbon and hydrogen and at least one other element and a relatively rigid top coating comprising a thermoplastic synthetic resin.

2. A container comprising a body, a top and a bottom of sheet metal and at least the interior of which is coated with a relatively flexible prime coating comprising a synthetic rubber selected from the group comprising a hydrochloride 0! rubber, a polychloroprene, a. plasticized polyvinyl chloride and a copolymer of butadiene and acrylonitrile, and a relatively rigid top coating comprising a thermoplastic synthetic resin.

3. A container comprising a body, a top and a bottom of sheet metal and at least the interior of which is coated with a relatively flexible prime coating comprising a synthetic rubber consisting of a copolymer of butadiene and acrylonitrile and a relatively rigid top coating comprising a thermoplastic synthetic resin.

4. A container comprising a body, a top and a bottom of sheet metal and at least the interior of which is coated with a relatively flexible prime coating comprising a chloroprene and a relatively rigid top coating comprising a thermoplastic synthetic resin.

5. A container comprising a body, a top and a bottom of sheet metal andat least the interior of which is coated with a relatively flexible prime coating comprising a plasticized polyvinyl chloride and a relatively rigid top coating comprising a thermoplastic synthetic resin.

6. A container comprising a body, a top and a bottom of sheet metal and at least the interior of which is coated with a relatively flexible prime coating comprising a synthetic rubber consisting of a hydrochloride of rubber and a relatively rigid top coating comprising a thermoplastic synthetic resin.

JACQUE C. MORRELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,259,496 Soday Oct. 21, 1941 2,378,445 Soday June 19, 1945 

2. A CONTAINER COMPRISING A BODY, A TOP AND A BOTTOM OF SHEET METAL AND AT LEAST THE INTERIOR OF WHICH IS COATED WITH A RELATIVELY FLEXIBLE PRIME COATING COMPRISING A SYNTHETIC RUBBER SELECTED FROM THE GROUP COMPRISING A HYDROCHLORIDE OF RUBBER, A POLYCHLORPRENE, A PLASTICIZED POLYVINYL CHLORIDE AND A COPOLYMER OF BUTADIENE AND ACRYLONITRILE, AND RELATIVELY RIGID TOP COATING COMPRISING A THERMOPLASTIC SYNTHETIC RESIN. 